Punch and die holder with eccentric stripper spring



g- 28, 1956 P. H. TAYLOR 2,760,574

PUNCH AND DIE HOLDER WITH ECCENTRIC STRIPPER SPRING Filed Feb. 15, 1952 I INVENTOR.

PUNCH AND DIE HOLDER WITH ECCENTRIC STRHPER SPRING Paul H. Taylor, Grand Island, N. Y.

Application February 15, 1952, Serial No. 271,805

9 Claims. (Cl. 16494) This invention relates to a work-perfoming instrumentality of the type characterized by a resilient means in which energy is stored during working strokes of the instrumentality so that such energy may be released upon completion of the working strokes to restore, or aid in restoring, the instrumentality or parts thereof, to their original positions.

An instrumentality of the type generally described is disclosed in United States Patent 1,955,866, granted to George F. Wales on April 24, 1934, and which is concerned with perforating work-pieces in the form of sheets. ln such an instrumentality, the punch and die and the holder by which the punch and die are maintained in operative alignment provide a unitary assembly which may be employed in connection with other similar assemblies to punch a predetermined hole pattern in a workpiece. The instrumentality, or instrumentalities, as the case may be, are adapted to be employed in connection with a punch press, the ram of the press being availed of to drive the punches through the work-pieces to perforate the latter. During a working stroke of such an instrumentality, energy is stored in a preloaded spring surrounding the punch, which energy is released during the return movement of the ram to withdraw the punch from the work-piece preparatory to a succeeding working stroke.

In order to prevent binding of the punch, thereby impairing the effectiveness of the stripping spring during withdrawal strokes of the punch, it has been the practice, as shown in said Wales patent, to mount the stripping spring around and coaxially of the punch so that the energy which is released by the stripping spring will act along a line coincident with the axis of the punch. While such an arrangement will minimize binding of the punch, the use of stripping springs in the manner described has serious disadvantages. Such springs require considerable space and hence increase the height of the punch column, They also add considerably to the Width of the assemblies and thereby prevent the forming of holes as close together as would otherwise be possible. Moreover, the diameter of the springs is determined by the diameter of the punch which may not necessarily have any relation to the optimum spring diameter required to produce the necessary stripping force.

The principal object of the invention is to overcome the above objections, this object contemplating an instrumentality of the character described which is so designed that the resilient means in which energy is stored may be located wholly at one side of the punch, or other element, to be acted upon after completion of the working stroke of the punch or element.

A further object is to provide an instrumentality which is so designed that the resilient means may be located at one side of the element to be acted upon by the resilient means without causing binding of said element in the guide in which it is movable.

A still further object is to provide an instrumentality having dimensions which are determined primarily by the nited States Patent element which performs the working strokes and which are not increased objectionably by the resilient means which acts upon said element upon completion of its working strokes, the instrumentality so characterized having the advantage that when employed for perforating operations, and in groups, the perforations in the workpieces may be formed much closer together, if desired, than has heretofore been possible.

A still further object is to provide an instrumentality wherein the means for preventing binding of the reciprocatory element is availed of in the event that the element is cylindrical in shape, to prevent rotation of said element during working and return strokes.

A still further object is an instrumentality wherein the means for preventing binding between the reciprocatory element and the part in which it is guided is also available to limit the range of movement of the stroke of the element.

A still further object is to provide an instrumentality wherein the advantages set out above may be attained while at the same time permitting pre-loading of the resilient means to any degree desired.

Still another object is to provide, in an instrumentality having a reciprocatory tool, a novel means acting as a limit stop for controlling rectilinear movement of the tool and preventing over-travel thereof, and which further acts as a rolling anti-friction means for the tool.

A further object is to provide an instrumentality of the character set forth in which a novel means is employed for keying reciprocatory tools against rotation, particularly when such tools are of other than circular cross section and must be accurately aligned and oriented with respect to cooperating parts.

Another object of the invention is to provide an instrumentality having a reciprocatory tool and a guide element in which the tool is axially movable and wherein the guide element also serves to support the resilient means in eccentric relation to the axis of the tool.

A related object is to provide a perforating unit in which the punch and its guide are operable to confine a pre-loaded stripping spring at one side of the punch in such a manner that the punch, its guide and the strip ping spring comprises a self-contained assembly.

A still further object is a novel design and arrangement of the parts of the instrumentality, whereby to pro vide for simplicity and economy in construction and facilitate assembling and disassembling of said parts.

The invention is illustrated in the accompanying drawings, wherein:

Figure 1 is a side elevational view, partially in section, of an instrumentality embodying the features of the invention;

Figure 2 is a fragmentary view of that portion of the instrumentality shown in section in Figure 1 and illustrates the relative positions of the parts upon completion of the perforating stroke of the punch;

Figure 3 is a detailed section taken along line 33 of Figure 1; and

Figure 4 is a similar section taken along line 4--4 of the same figure.

The features of the invention are illustrated by way of example in connection with a perforating assembly of the general type disclosed in said George F. Wales Patent 1,955,866.

The perforating apparatus, as illustrated, is unitary in character and includes a U-frame 20 having a base member 21 and an arm 22. The base member and arm are connected by a shank 23 and are spaced apart to provide a throat 24. At its outer end, the arm 22 is formed with a vertical bore 25 which, as best shown in Figure 4, is elongate in transverse cross section, the end walls being semicircular in outline with the 'radius of the paveo sn outer end wall being greater than the radius of the inner end wall.

The bore 25 accommodates a stripping element 26 Y which at its lower end 27 is in the form of a sleeve. The

'ment and the bore in which: the latter moves is such as to prevent turning movements of-the-element in the bore.

However, ifdesired a pin 30- having an innerend which extends into a vertical slot 31 in the element'26 may also be employed for this purpose.

The bore 32 throughthe stripping element accommodates, and serves as a guide for, the punch 33 of the perforating assembly,-the-upperend of-thepunch-being cylindrical incross section-and thebit end- 34,- as illustrated, being oval (Figure-4).

The upper end of the punch 33 isformed'with a head '35 which is elongate in-shape-and which extendsrearwardly across the bore 25 andover the arm 22. The extension 29 on theelement -26"and the'head 35 ofthe punch provide opposed seats for a stripping-spring 36, the latter being located to the rear ofthe punch 33 and the lower end being accommodated in the rear portion of the bore 25. The stripping spring 26 is preferably preloaded and is normally operative to hold the lower end of the bit portion of the punch'retracted with respect to the lower end ofthe stripping element 26, as illustrated in Figure l. Upward movement of the punch 33 with respect to the stripping element 26 is limited byan antifriction element in the form of a-ball' 37L The latter, 1 in the retracted position of the punch, is located at-'the upper end ofa guide channel 38 in the sleeve extension 28 and inthe lower end of a similar channel 39 in the punch 33. The upper end wall of the guide channel 38 and the lower end wall of the'g'uide channel '39 -and' the ball 37 provide positive means for limiting upward movement of the punch 33 with-respect to the stripping element 26. "An opening40'which communicates with'the guide channel 38 is provided to-enable insertion of the ball 37 into-the guide channels 38 kind.

The punch 33, stripping element 26; strippingspring 36 and ball 37 provide a unitary assemblyJ-Saidassembly is normally held in an elevated-position by a lifting spring 41 which is located between seatsformed :on' the undersideof' the head '35 of :the punchtand the upper arm of the frame 20.

The outer end of the base member 21 carries a die 42 having an aperturewhich corresponds in shape to the punch bit, a passage 43being formed inth'e oute'r end of the base member 21 and communicating-with the'aperture in the die 42 to provide for discharge-'of'slugs punched from workpieces.

Operation of the perforating device, asnotedfmay be effected by any suitable press. The latter is' 'sufi'iciently illustrated for the purpose in view, in Figure-2, by-show- -ing of the bed 44 "and the ram45. ln 'th'e 'useof the perforating apparatus, 'assuming'the latter to be arranged in a press with the basemember 21 resting upon the bed 44, as illustrated, a work-piece 46 to be perforated,

' is'in'troduced between thepunch'and dieofth'e device as illustrated in Figure 1. Upon operation 'of theram of the press, the punch through the agericy of the spring 36 moves the lower-end of the stripping'element 26"into engagement with the top surface of the-'work-pieceythe lifting spring 4-1 being compressed asthis occurs? As the ram of the press continues downwardly, the punch "33 driven through the work-piece'46, as illustrated in Figure 2, the stripping spring 36 thereby being compressed and the'lifting spring 41 being further compressedl "'After the perforating stroke has been completed, and as the ram of the press is retracted, the spring 36 is operative to withdraw the punch 33 from the work-piece, the limit of such movement being, as noted, determined by the ball 37. After the punch= has been withdrawn from the work-piece in the manner described, the lifting spring 41 is operative to elevate the punch, stripping "element and stripping spring'assembly so'that'the lower end of the stripping element is-retracted -far=enough to permit shifting of the work-piece preparatory to a second operation, or withdrawalofthe work-piece"preparatory= to the introduction of another worlepiece.

It will be noted that as the stripping spring 36 is located at one side of the punch 33 it will, as it acts against its seats tend to rock the punch 33 in the stripping element 36. Such action, unless provision is-madetoguard against t :this,- will cause binding between. the-punch and the stripping element- 26- and-thereby render the stripping spring ineffective, or-reduce its effectiveness- In accord- 1 ance with the present invention, any such-tendency of the -punch to rock in the-element 2 6 is in a direction which results only in greater pressure being transmit-tedirom the punch to the upper extension- .on' the guide element 26 through the ball 37. Hence, -it will be apparentth'at as the punch in -the guide element, these two parts cannotbind.

The spring36, therefore-, willbe effective to withdraw -the punch from the work-piece' and-its effectiveness is not impaired by binding between the-punch and the guide ele- -ment;- The ball 37 also prevents relative 'rotative movements between the punch and theguide element.

The location of the stripping spring'36-and lifting spring 41 behind the punch and inline with the arm 22 provides a -unitary assembly-which is narrow-:and whose width is not increased inany'nraterial degree byrvirtue of theuse of stripping "and-lifting springs in the manner contemplated. The-perforating device, therefore,ha's the advantage that when employed in"groups,'holes.may be formed in'the work-piece whichareclosely spaced, much more closelwspaced than ispossible in perforating devices of the type wherein the stripping spring surrounds the punch in coaxial relation'with respect thereto or in-a'ssemblies :wherein' a plurality of strippingsprings are arranged around the' punch' in such a manner as to exert equal J forces at opp'osite sides of the punch.

L While-thefeatures of th'e'invention are illustrated in "connectionwit-h a'p'erfora-ting assembly, it is to be under- 'antages resuI-ting'from its use may be attained in-connecstood th'at'the -inv'ention' is not so limited and that the ad- I tion"wi'th 'various instrumentalities which require the use of 'a-re'silient means which is compressed during the worki ing-stroke of an element so that the energy stored thereinrnay be released upon completion"of-such'wotking -"st'roketo' restore, or aid inresto'ring, the element to its "original position.

rate awork-piece, resilient means which is located wholly at one side laterally of said punch, and which is interposed between'said punch and saidsleeveand' which rea'ctsfaga'inst 'said'sleev'e and 'isr'oper'atively' connected to said punch to be" compressed during the working stroke of the latter and which isoperative, upon expansion, to

withdraw the punch from said work-piece, said sleeve and punch being'formed with confronting channelswhich "extend in the direction of movement of said punch "and whicharedoc'ated at the opposite side laterally of said punchfroin said resilient means, eachof said channels being of limited axial extent and being closed a t its ends, a rolling'anti fri'ction element in saidchannels for pre- Veriting 'binding'of said punch in said sleeve when said resilient means is acting on said punch for the purpose described, said anti-friction element cooperating with opposite ends of said channels to limit withdrawal movement of said punch with respect to said sleeve, and a second resilient means interposed between said punch and said holder for elevating said punch, sleeve and first mentioned resilient means after withdrawal of said punch from said work-piece.

2. In a perforating assembly, an elongated holder, a sleeve reciprocable in said holder and having a bore and a seat wholly at one side of said bore, a punch reciprocable in said bore and having a head which provides a second seat aligned with the first-named seat, a die with which said punch cooperates to perforate a work-piece, resilient means which is located wholly at one side laterally of said punch between said seats and which is compressed during the working stroke of said punch and which is operative, upon expansion, to withdraw the punch from said workpiece, said sleeve and punch being formed with confronting channels which extend in the direction of movement of said punch and which are located at the opposite side laterally of said punch from said resilient means, each of said channels being of limited axial extent and being closed at its ends, a ball in said channels for preventing binding of said punch in said bore when said resilient means is acting on said punch for the purpose described, said ball cooperating with opposite ends of said channels to limit withdrawal movement of said punch with respect to said sleeve, and a second resilient means interposed between said punch and said holder for elevating said punch, sleeve and first mentioned resilient means after withdrawal of said punch from said work-piece, said punch and said first and second mentioned resilient means being located in a linear series which extends lengthwise of said holder.

3. Perforating apparatus comprising a holder, a sleeve reciprocable axially in said holder, a punch reciprocable axially in said sleeve, a single resilient means located wholly at one side laterally of said punch between said sleeve and said punch to be compressed on the working stroke of said punch relative to said sleeve and which is is operative, upon expansion, to withdraw the punch from the work, said sleeve and said punch being formed with confronting channels which extend in the direction of movement of said punch and which are of limited axial extent and are closed at their ends and which are disposed at the diametrically opposite side laterally of the axis of said punch from said resilient means, and a rolling, antifriction element engaging in said channels and connecting said punch and said sleeve, said sleeve, punch, and resilient means constituting an assembly unit, and resilient means interposed between said unit and said holder for constantly urging said unit as a whole to its original position.

4. Perforating apparatus comprising a holder, a sleeve reciprocable axially in said holder and having a seat at one side, a punch reciprocable in said sleeve and having a lateral extension which is provided with a seat aligned with the first-named seat, resilient means located wholly at one side laterally of the axis of said punch and interposed between said seats and which is compressed when said punch is moved relative to said sleeve on the working stroke of said punch and which is operative to, upon expansion, withdraw said punch from the work, and a lostmotion connection between said punch and said sleeve including anti-friction means disposed between said punch and said sleeve at the opposite side laterally of the axis of said punch from said resilient means, said sleeve, punch, and resilient means constituting an assembly unit, and resilient means interposed between the lateral extension of said punch and said holder for constantly urging said unit as a whole to its original position.

5. Perforating apparatus comprising a holder, a sleeve reciprocable axially in said holder and having a seat at one side, a punch reciprocable in said sleeve and having a lateral extension which is provided with a seat aligned with the first-named seat, resilient means located wholly at one side laterally of said punch and interposed between said seats and which is compressed when said punch is moved relative to said sleeve on the working stroke of said punch and which is operative, upon expansion, to withdraw said punch. from the work, said sleeve and said punch being formed with confronting channels at the opposite side laterally of said punch from said resilient means which extend in the direction of movement of said punch and which are closed at their ends, and rolling anti-friction means which engages in both of said channels and which is operative to prevent binding of said punch in said sleeve and to limit the movement of said punch in the sleeve, said sleeve, punch and resilient means constituting an assembly unit, and resilient means interposed between the lateral extension of said punch and said holder for constantly urging said unit as a whole to its original position.

6. Perforating apparatus comprising a holder, a sleeve reciprocable axially in said holder and having a seat at one side, a punch reciprocable in said sleeve and having a lateral extension which is provided with a seat aligned with the first-named seat, resilient means located wholly at one side laterally of said punch and interposed between said seats and which is compressed when said punch is moved relative to said sleeve on the working stroke of said punch and which is operative, upon expansion, to withdraw said punch from the work, and a lost-motion connection between said punch and said sleeve comprising a rolling anti-friction element disposed between said punch and said sleeve at the opposite side laterally of said punch from said resilient means, said punch and sleeve being provided with confronting channels which extend in the direction of movement of both said punch and sleeve and which are of limited axial extent and closed at their ends, said anti-friction element engaging in both said channels and being movable therein, said sleeve, punch, and resilient means constituting an assembly unit, and resilient means interposed between the lateral extension of said punch and said holder for constantly urging said unit as a whole to its original position, said holder comprising a C-frame having upper and lower arms, said assembly unit being mounted reciprocably in said upper arm, and a die aligned With said punch mounted in said lower arm, both said resilient means being coil springs, and the axes of said punch and both said springs lying in a common plane extending in the direction of longitudinal extent of said arms.

7. Perforating apparatus comprising a holder, a sleeve reciprocable axially in said holder and having a seat at one side, a punch reciprocable in said sleeve and having a lateral extension, which is provided with a seat aligned with the first-named seat, resilient means located wholly at one side laterally of said punch and interposed between said seats and which is compressed when said punch is moved relative to said sleeve on the working stroke of said punch and which is operative to, upon expansion, withdraw said punch from the work, said sleeve and said punch being formed with confronting channels at the opposite side laterally of said punch from said resilient means which extend in the direction of movement of said punch and which are closed at their ends, and a rolling anti-friction element which engages in both :of said channels and which is operative to prevent binding of said punch in said sleeve and to limit the movement of said punch in the sleeve, said sleeve, punch and resilient means constituting an assembly unit, and resilient means interposed between the lateral extension of said punch and said holder for constantly urging said unit as a whole to its original position, said holder comprising a C-frame having upper and lower arms, said assembly unit being mounted reciprocably in said upper arm, and a die aligned with said punch mounted in said lower arm, both said resilient means being coil springs and the axes of said 

